A developer using Oracle Cloud Infrastructure (OCI) API Gateway must authenticate the API requests to their web application. The authentication process must be implemented using a custom scheme which accepts string parameters from the API caller. Which method can the developer use in this scenario? (Choose the best answer.) 

Answer options:

A. Create an authorizer function using request header authorization.
B. Create an authorizer function using token-based authorization.
C. Create a cross account functions authorizer.
D. Create an authorizer function using OCI Identity and Access Management based authentication.

A